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Photochemical reactivity does not always align with absorption spectra, and this work uncovers why. Through studies of photocycloadditions, our researchers show that selective excitation of chromophores in different microenvironments drives wavelength-dependent reactivity by altering excited-state lifetimes. Time-resolved fluorescence confirmed this mechanism, and tethering chromophores highlighted the critical role of microenvironments. The findings provide a framework for controlling light-driven processes across fields such as manufacturing and phototherapy.

Our researchers have developed a new class of visible-light-responsive fluorophores, called hemipiperazine-based IndHPIs and PyrHPIs, that overcome common limitations of small-molecule photoswitches. These compounds show large Stokes shifts, excellent thermal stability, high fatigue resistance, and reversible fluorescence switching under red light. Some are readily taken up by living cells, where glutathione helps regenerate the brighter isomer, making them promising tools for super-resolution imaging and advanced optical materials.

At the Karlsruhe Institute of Technology, researchers are developing tiny artificial heart valves with 3D printing, using collagen from bacteria as the base material. This collagen, once intended for cosmetic fillers, can be combined with a patient’s own cells to create personalized implants. The team is also working on bioprinted corneas, where stem cells derived from a patient’s skin are grown into functional tissue designed to minimize the risk of rejection.